What is the ruling on a married man conversing with girls online, and how can he rid himself of this bad habit, especially since it has led to his neglecting prayers and a change in his behavior?

A married man's conversations with foreign women are a great evil and a severe sin. His neglect of prayer and his irritability might be consequences of this disobedience. It is advisable to supplicate for him, for the wife to adorn herself for him, and to advise him kindly for his repentance. If he repents and rectifies his conduct, especially concerning prayer, then that is good. If he does not rectify his conduct, one can seek help from close relatives to advise him. If there is no benefit in remaining with him, it is then desirable for the wife to seek separation.